COVID toes, newborn blue toes, and prepartum SARS-CoV-2 infection – Authors' reply
Authors: Christoph Hochmayr, Ursula Kiechl-Kohlendorfer, Elke Griesmaier
Journal: The Lancet (2023)

We thank Ya Bin Zhou and Zi Gang Xu for their interest in our Clinical Picture1Hochmayr C Auckenthaler M Fink F-M Kiechl-Kohlendorfer U Griesmaier E Differential diagnosis of blue toes in a newborn baby: might have been maternal infection with COVID-19?.Lancet. 2023; 401: e20Summary Full Text Full Text PDF PubMed Scopus (2) Google Scholar and their critical considerations. Following the first description of blue toe syndrome,2Karmody AM Powers SR Monaco VJ Leather RP "Blue toe" syndrome. An indication for limb salvage surgery.Arch Surg. 1976; 111: 1263-1268Crossref PubMed Scopus (122) Google Scholar Jan V Hirschmann and Gregory J Raugi defined blue toe syndrome as the development of "blue or violaceous discoloration in one or more toes in the absence of obvious trauma, serious cold-induced injury, or disorders that produce generalized cyanosis", which is consistent with the presentation in our patient.3Hirschmann JV Raugi GJ Blue (or purple) toe syndrome.J Am Acad Dermatol. 2009; 60: 1-20Summary Full Text Full Text PDF PubMed Scopus (67) Google Scholar Furthermore, they say: "The affected digits are often painful."3Hirschmann JV Raugi GJ Blue (or purple) toe syndrome.J Am Acad Dermatol. 2009; 60: 1-20Summary Full Text Full Text PDF PubMed Scopus (67) Google Scholar Our patient was secondary transferred to our neonatal intensive care unit after birth, but acute pain at the moment the blueish colouration occurred was not reported by our colleagues. Proximal lesions in the arterial tree were initially identified as a potential source of thromboemboli, describing the most common source of blue toe syndrome.3Hirschmann JV Raugi GJ Blue (or purple) toe syndrome.J Am Acad Dermatol. 2009; 60: 1-20Summary Full Text Full Text PDF PubMed Scopus (67) Google Scholar Since the original description in 1976, other causes have been suggested, including conditions leading to decreased arterial perfusion, impaired venous outflow, and abnormal circulating blood. Chilblain-like lesions, or COVID toes, are a dermatological manifestation associated with COVID-19. Our patient showed blueish-coloured skin lesions at 12 h after birth, echocardiography was normal, and neonatal RT-PCR for SARS-CoV-2 infection was negative. This is in accordance with Cristiana Colonna and colleagues,4Colonna C Monzani NA Rocchi A Gianotti R Boggio F Gelmetti C Chilblain-like lesions in children following suspected COVID-19 infection.Pediatr Dermatol. 2020; 37: 437-440Crossref PubMed Scopus (83) Google Scholar who presented four paediatric patients with chilblain-like lesions following suspected SARS-CoV-2 infection. However, in discordance with our case, a cutaneous manifestation appeared several days after the systemic symptoms and in three of four patients the lesions subsided without sequelae.4Colonna C Monzani NA Rocchi A Gianotti R Boggio F Gelmetti C Chilblain-like lesions in children following suspected COVID-19 infection.Pediatr Dermatol. 2020; 37: 437-440Crossref PubMed Scopus (83) Google Scholar The causality of maternal COVID-19 during pregnancy and newborn blue toe syndrome remains debatable. Risk factors for thromboembolic events are various, including the formation of thrombi in the placenta or antibodies crossing the placenta. Also, an exaggerated immune response in the tissue, indicated by elevated concentrations of type I interferons, could have caused the discolouration. Our patient underwent a complete blood cell count and thorough laboratory investigation, but we could not prove a potential hypercoagulable state. Acute infections are associated with transient positive antiphospholipid antibodies, but in the case of SARS-CoV-2 infection, this is incompletely understood5Aubignat M Godefroy O COVID-19 and ischemic stroke: should we systematically look for lupus anticoagulant and antiphospholipid antibodies?.Rev Neurol. 2020; 176: 505-506Crossref PubMed Scopus (17) Google Scholar and was not further investigated in our case. Among a long list of various risk factors for blue toe syndrome, infectious inflammation is described most frequently and has also been discussed in the case of so-called COVID toes. In our opinion, however, COVID toes might for now just be considered another entity of blue toe syndrome. We declare no competing interests. Differential diagnosis of blue toes in a newborn baby: might have been maternal infection with COVID-19?A newborn baby girl with blueish-coloured skin lesions on the tips of the first, second, and fourth toes of her right foot was brought to our unit 12 h after birth (figure). Apart from the noted abnormalities, the patient was healthy; she was normally alert and showing no clinical signs of pain. The respiratory rate was between 40 and 50 breaths per min, oxygen saturation was over 95% on room air, heart rate was between 120 and 140 beats per min, and temperature was 36·5°C. No history of mechanical or physical damage and no familial predisposition to thromboembolic events or autoimmune diseases was reported. Full-Text PDF COVID toes, newborn blue toes, and prepartum SARS-CoV-2 infectionWe appreciate Christoph Hochmayr and colleagues1 sharing a case of a newborn baby with blue toes. However, we disagree with the diagnosis given for this case. Full-Text PDF